Intermittent grip device



March 19, 1935. F, c E

INTERMITTENT GRIP DEVICE 2 Sheets-Sheet 1 Fild Oct. 31, 1952 March 19, 1935. F. c. AREY 1,995,197

INTERMITTENT GRIP DEVICE Filed 091:. 31, 1932 2 Sheets-Sheet 2 Patented Mar. 19, 1935 PATENT orricr.

, v 1,995,191 INTERMITTENT GRIP DEVICE Fred C. Arey, Oak Park, 111., assignor to Vulcan- Soot Blower Corporation, a corporation of Pennsylvania Application October 31,

10 Claims.

Specifically considered, the present invention has for its object to produce a simple and novel means for turning atubular soot cleaning element step by step. t

Sometimes the heat to which tubular soot cleaning elements for boiler tubes are subjected causes them to become distorted, thereby necessitating the application of considerable force to turn the same. In one of its aspects, the present invention may be said to have for its object to produce a simple and novel turning means for sucha cleaning element, or other element, in which the motive force is multiplied many times before being applied to the element to turn the same.

It is, of course, possible to secure a desired multiplication of the applied force by using levers of the proper length and ratios as to their arms. However, the space available for .the operating means by which a cleaning element or other element is to be turned is often limited so that long levers could not be employed even if they were not otherwise objectionable. Viewed in one of its aspects, the present invention may be said to have for its object to produce in a simple and compact form a step by step driving mechanismin which the leverage or multiplication of force is very much greater than has hereto-- fore been obtainable without the employment of objectionably long levers. 1

In carrying out my invention, I fix on the element to be turned a ratchet wheel and mount on said element beside the ratchet wheel a pawlcarrying arm free to swing on saidelement. On the arm is pivoted a pawl provided with a slot or other means including two'parallel separated guiding surfaces. The pawl and the arm carrying the same are driven by a pin or roller extending into the slot or between the guide surfaces on the pawl and having a diameter approximately equal to the width of the slot or the spacing between the guide surfaces. The pin or roller is mounted and supported so as to be capable of revolving bodily about an axis spaced apart from and parallel to the axis of the pin or roller and the axis of-the element tobe turned. The radius of the path in which the pin' or roller travels is made short so that, as the pin or roller travels in a circle, continuously in one direction, it drives the pawl and the pawl-carrying arm in a manner to give the element to be turned a stepby step movement, one step for each complete revolution of the pin or roller. This arrangement is particularly useful for the purpose of first driving the element to be turned 1932, Serial No. 640,373

in one direction and then in the other direction; the pawl being madedouble-ended so that, as long as the driving pin or roller revolves about its axis of rotation in one direction, the element to be turned moves step by step in the same direction whereas, when the direction of the turning movement of the pin or roller is reversed,

the member to be turned will also begin to move step by step in the reverse direction. I

Therefore viewed in one of its aspects, the present invention may be said to have forits object to produce a simple and novel mechanism for turning an element step by stepin either direction by means of a continuously rotating crank pin or the like, the direction in which the element turns depending on the direction in which the-crank pin or the like turns and changing with the same. l Viewed in another of its aspects, the present invention may be said to have for its object to produce a 'simple' and novel reversing step by step drive in which 'a double-ended pawl is hung upon a swinging arm, the pawl and the arm being driven by a continuously rotating crank pin or the like, turning first in one direction and then in the other, wherein the proper end of the paw'l will always be engaged with the ratchet wheel at the beginning of a working stroke, without moving the pawl-carrying arm until such engagement is effected.

The various features of novelty whereby my invention is characterized 1 will hereinafter be 1 pointed out with particularityin the claims; but, for a full understandingof my-invention and of its objects and advantages, reference maybe had to the following detailed description taken in connection with the accompanying drawings, wherein: k V a V Figure 1 is a longitudinal central section, through the head end of a soot cleaning element embodying the present invention; Fig. 2 is an end view of the apparatus; vFig. 3 is a sectionv on line 3-3 of Fig. 1; Fig. 4 is atop plan View of the pawl, pawl carrier. and the operating member therefor, the bearing for the operating member being shown in section; andzFig. 5 is a bottom plan view of a fragment of the cleaning element, showing the ratchet wheel, the pawl carrier, and the brake for the latter.

In the drawings the inventionis illustrated as applied to a tubular soot cleaning element and, for the sake of brevity, the detailed description will be confined to this particular use; butit will,

of course, be understood that the invention may anti-friction bearings.

be applied to efiect a step by step movement of any other element.

Referring to the drawings, 1 is a tubular cleaning element adapted to discharge jets of steam or other cleaning fluid against the tubes of a boiler of which only a fragment of the boiler setting 2 is shown. 3 is a tubular extension of the cleaning element properand may be regarded as forming a part of the latter. Connected to the free end of the member 3 is a hollow head 4 which supplies the cleaning fluid; the head being stationary and the member 3 being rotatable in the head. All of these parts are old. The present invention has to do with the mechanism for turning an element which, in-the present instance, is the tubular cleaning element, about its long axis. In the arrangement shown, there is keyed to the cleaning element device a ratchet wheel 5, the ratchet wheel being preferably on the member 3. Loose on the member 3, beside the ratchet wheel, is a pawl-carrying arm 6 having a disk-like thick 'ened hub portion '7 provided with a' projecting circumferential head 8. This arm carries at its outer, end a pawl9; the pawl being mounted on a journal or pivot pin-10 fixed to the arm 6 and lying parallel with the cleaning element. .The pawl is provided with two dog? members 11 and 12 diverging from each other. The parts are so pro portioned that,-when the pawl, whichlies inthe plane of the ratchet wheel, is symmetrically disposed with respect to a line passing through the pivotal'axis thereof and through the axis of the cleaning element, as shown in Fig. 3, both dogs are out of engagement with1the ratchet wheel. Consequently, when the pawl is .tilted in the clockwise direction,=,as viewed in Fig. 3, the dog 12 will move intoengagement with the teeth on the ratchet wheel, whereas the dog 11 will lift still farther away from the wheel. When the pawl is tilted in the opposite direction, the dog 11 engages with the ratchet teeth and the dog '12 is elevated: With this arrangement, by properly shifting the pawl on itssupporting arm and oscillating the arm, the ratchet wheel may be turned step bystep in either direction.

Novel means areprovided for oscillating the pawl on its supporting arm and for oscillating the arm through working and return strokes. In the specific arrangement illustrated, the driving member is a rotatable shaft 14 parallel to the cleaning element and having its long axis spaced apart from the axisof the cleaning element a radial distance slightly greater than the radial distance between the pivotal axis of the pawl on its supporting arm and the axis of the cleaning element. This shaft is supported in bearings in a'bracket or pedestal 15 rising from the head 4 and a heavy platel6 forming one wall of a housing for thepawl and ratchet mechanism and connected to the head 4 by means of long, strong bolts 17 surroundedby sleeves 13 that space the member 16 and the head apart from eachother. Spaced apart from the wall 16, and lying on the opposite side of the pawland ratchet mechanism from that on which the wall 16 is locatedQis a Second wall 19 which, witha connecting annular wall 20 of sheet metal, completes the casing 01' housing for the "pawl and ratchet mechanism. On the end of the shaft-14, within this casing .,or housing, is a short crank 21 having thereon a crank pin 22 whose axis is spaced only a short distance from'the 'axis of the" driving shaft 14. In order to reduce friction, I prefer to mount on the crank pin a wheel or roller 23 supported by This wheel or roller exof the pawl and the axis of the driving shaft, ex-

tended, when the parts are in such positions that the axes of the cleaning element, of the driving shaft, and of the pivot or journal for the pawl are all in thesame plane. Consequently, when the driving shaft is turned in either direction, the crank pin at times lies outwardly from the pivot for the pawl, and sometimes inwardly therefrom. As the driving shaft revolves, carrying the crank pin with it, the crank pin acts on the sides of the trough in the pawl and causes the pawl to swing on its supporting arm.

Assuming that the parts. are 'in the positions indicated in Fig. 3 and that the driving shaft is being operated to cause the crank pin to travel in the clockwise direction, it will be seen that the action of the crank pin will be to swing the pawl in a clockwise direction, provided that there is less resistance to movement on the part of the pawl than to swinging movements by the pawlcarrying arm. Should the pawl-carrying arm be movable under a lesser pressure than that required to tilt the pawl, the only result would be an oscillation of the pawl-carrying armwithout producing any engagement of the pawl with the ratchet wheel. However, if the pawl-carrying arm be held against rotation until the dog 12.has been swung down into engagement with the teeth on the ratchet wheel, thena continued movement of the crank pin will cause the pawl andthe arm i to travel ahead'together, with the pawl driving theratchet wheel; I have therefore provided a brake that holds the pawl-carrying arm against turning'movements sufi'iciently toinsure that the pawl may make its necessary rocking movements on the pawl-carrying arm while the'latter is standing still; but not offering sufiicient resistance to turning or swinging movements of the pawl-carrying. arm to interfere with efficient operation of the latter. shown, the brake consists of two arms, 25 and 26, lying on opposite sidesof the cleaning element in the plane of thehub portion of the pawl-carrying arm. Corresponding ends of the arms 25 and 26 are provided with seats 2'7 partially embracing stationary abutments 28 in the housing or casing, to permit the arms to rock. The opposite ends of the arms are connected together by a tension spring 29. Each of the arms 25 and 26 has thereon a brake shoe BOgrooved to fit over the annular rib-. or, projection 8 and thus be held against slipping off the hub of the pawlecarrying arm in the lateral direction.

Consequently, when the crank pin travelsin the clockwise direction, as viewed in Fig. 3, with the parts initially positioned as there shown, the brake device holds the pawl-carrying arm sta tionary, so that the first part of the movement of the crank pin results in a tilting or swinging of the pawl to bring the dog 12 into engagement withthe teeth on the ratchet wh el. Further movement of the crank pin results in a clockwise turning movement of the cleaning element. The turning movement of the ratchet wheel ceases after the crank pin has traveled through In the arrangement an anglesomewhat greater than ninety degrees and then a slight counter-clockwise swinging movement of the pawl about its pivot takes place. However, as soon as the center of the crank pin passes below the arc-shaped path of the pivot for the pawl, the pawl is again swung in the clockwise direction before any pressure tending to drive the ratchet wheel backwards can be exerted. After the crank pin has made half a revolution it is pressing against the left-hand side of the wall or trough or slot, either below or above the arcshaped path in which the pivot of the pawl travels, thus causing the dog 12 to be swung into contact with the periphery of the ratchet wheel and the pawl-carrying arm to swing toward the left. During the last half of the movement of the crank pin through one complete revolution, the arc of the crank pin passes on the other side of the pawl pivot pin, causing a slight clockwise pressure on the pawl while the pressure on the pawl-carrying arm is counterclockwise; thus holding the dog 11 out of engagement with the ratchet wheel on the return stroke of the pawl arm. As long as the driving shaft continues to be turned in the clockwise direction, the cycle just described will be carried out during each revolution of the shaft, and the cleaning element will be driven in the clockwise direction step by step, one step during each revolution of the driving shaft. However, because of the peculiar construction and arrangement of the parts, when the direction of rotation of the driving shaft is reversed, the dog 11 of the pawl becomes the active one and the cleaning element is turned step by stepin the counter-clockwise direction.

- The driving shaft is turned by means of a wheel or sheave 32 of comparatively large diameter,'fixed-to the outer end of the shaft- In the peripheral trough of the wheel are sprocket teeth 33 engaged with an endless chain 34. By pulling upon one of the depending stretches or runs of the chain, the driving shaft will be caused to turn in one direction. When the other stretch or run is pulled down, the direction of rotation of the driving shaft is reversed. The driving wheel or sheave, without being" so large as to destroy theidea of compactness in the construction as a whole, may have a diameter much greater than the radius of the crank that operates on the pawl and pawl-carrying arm. Again, the crank pin acts on the long arm of the lever in driving the pawl and ratchet device. Consequently, the

force of a pull on the chain is multiplied many times before being transmitted to the element-to be turned; thus making it easy to turn the cleaning element even though the latter offers great resistance because of being distorted, or for any other reason. This powerful driving effort, as heretofore explained, is obtained without making any of the over-all dimensions of the structural apparatus large. For the sake of comparison, the driving mechanism of Patent No. 1,590,300, of June 29, 1926, may be regarded asrepresenting the old practice. In order to secure a lever arm of about 8 inches in the mechanism of that patent, the over-all width must be about 18 inches. With the present construction, having an overall width of about 7 inches, which is the diameter of the sprocket wheel, the same effect is obtained as though the lever arms of the mechanism in Patent No. 1,590,300 were inches long, producing an over-all width of between four and five feet.

.In the arrangement shown, the double-ended pawl is so proportioned that the pivotal axis thereof passes through the center of gravity, whereby the pawl is balanced and will remain in any position into which it may be placed. While the balanced 'characteristicis not essentialfor j.

the successful operation of the device, it is useful whenever the apparatus must be so set that the pawl-carrying arm 6 will not be vertical when in the neutral position which it occupies in Fig. 3. In other words, it may sometimes be necessary to set the head-in a position in which it is turned bodily, either in a clockwise direction or in a counter-clockwise direction, about the axis of the cleaning element, from the'vertical position illus* trated in the drawings. I

It will, of course, be evident that the cleaning element may be turned through any desired complete number of revolutions, step by step, by simply pulling onlthe'proper vertical stretch or run of the chain. Ordinarily, in the case of soot cleaning elements, it is not necessary or desirable to turn them'through complete revolutions, as otherwise there would be no necessity; for reversing their direction of angular movementsj On the other hand, after a cleaning element has been turned through an angle of less than 360, it is the practiceto turn it back again through the same angle. I have therefore provided means whereby the turning movement of the cleaning element, in either direction, may be arrested after any desired angular distance has been traversed. To this end, I haveprovided the ratchet "wheel 5 with a projecting hub 35. having distributed around the periphery a series of radial holes 36.

In the face of the ratchet wheel, at 'theinner' radially through the same and adapted to be. screwed into any one of the openings 36in the.

hub. When the blocks are' secured to the hub and the ratchet wheel is turned, the stationary stop 40 lies in the path of travel of the blocks; sothat, after the ratchet wheel has been turned through a predetermined angle in onedireotion, one of the blocks will engage with the stationary stop and, after the cleaning element has been turned in the" opposite direction through the same anglefthe second block will strike the stationary stop. Therefore, the operator simply pulls the' chain until it will move no farther, whereupon he will take hold of the opposite stretch or run of the chain and pull it to the limit of the movement permitted'by the stop device.

to the body of the bracket. The two runs of the chainare threaded through the openings in these projections and are thereby held in spaced relation to each other, while being permitted to.

' If desired, a guard may be provided to hold the move or swing laterally in the plane of the wheel or sheave.

It will thus be seen that I have produced a simple, compact pawl and ratchet-driving mechanism in which a powerful lever action is secured toaid in turning an element; in which a step by step turning movement results from a continuous movement in one direction ofthe driving member; and inwhich a reversal of the step by step movement is effected through a mere change in the direction of movement in the driving mechanism.

While I have illustrated and described with particularity only a single preferred form of my invention, I do not desire to be limited to the exact structural details thus illustrated and described; but intend to cover all forms and arrangement which comev withinthe definitions of my invention constituting the appended claims.

I claim: g

1. In combination, a member to be turned step by step in either of two directions, a ratchet wheel fixedto said member, an element mounted for oscillation aboutthe turning axis of said member, a double-ended pawl pivoted on said element in position to be swung into and out of engagement with said ratchet wheel, a short crank rotatable in either of two directions about an axis parallelwith the aforesaid axis and farther away from the latter than the pivot of the pawl, a crank pin on said crank, and guides on said pawl in sliding engagement with opposite sides of said crank pin. 2

2. An element adapted to be turned step by step in either of two directions, a driving member adapted to be continuously rotated, a ratchet wheel fixed to said element, a pawl arm adapted to swing about the axis of said element, a doubleended pawl on said arm adapted to cooperate with the ratchet wheel to turn said element in one of said directions-or; the other depending upon which end of the pawl engages with the ratchet wheel, and a pin and slot connection between said pawl and the driving member'including a crank pin on said member.

3. An element adapted to be turned step by step in either of two directions, a driving member adapted to be continuously rotated, a ratchet wheel fixed to said element, a pawl arm adapted to swing about the axis of said element, a balanced double-ended pawlon said arm adapted to cooperate with the ratchet wheel to-turn said element in one of said directions or the other depending upon which end of the pawl engages with the ratchet wheel, and a pin and slot on nection between said pawl and the driving member including a crank pin on said member.

4. An element adapted to be turned. step by step in either a backward or a forward direction,

.a ratchet wheel fixed to. said'element, a pawl arm adapted to swing about the axis about which said element turns, relatively to said element, a double-ended pawl pivotally mountedfon said arm in position to cooperate with said ratchet wheel, one of the ends of the pawl being adapted to turn the ratchet wheel in one direction and theother end of the pawl being adapated to turn the ratchet wheel in the opposite direction, a driving member rotatable about an axis parallel to the axis of theratchet wheel and spaced a considerable-distance apart from said axis, said pawl having therein a radial slot, a crank pin on said driving member spaced apart a short distance from the axis of rotation of the driving memberand projecting intosaid slot, said slot being at least as long as the diameter of the path of travel of the crank pin.

- 5. In combination, a ratchet wheel, a pawl arm, means for supporting the wheel and the arm adjacent to each other for independent angular movements about the axis of the ratchet wheel, a doubleeended pawl pivoted on said arm in position to permit either end to be swung into op:- erative relation to the teeth on the ratchet wheel topermit the wheel to be turned in either direction, said pawl having a radial slot at the center, a driving member rotatable about an axis parallel to the axis of theratchet wheel, and a crank pin carried by said driving member and projecting into the slot in the pawl, said slot being long enough to permit the crank pin to remain therein during the rotation of the driving member.

6. Incombination, a ratchet wheel, a pawl arm, means for supporting the wheel and the arm adjacent to each other for independent angular movements about the axis of the ratchet wheel, a double-ended pawl pivoted on said arm in position to permit either end to be swung into operative relation to the teeth on the ratchet wheel to permit the wheel to be turned in either direction, said pawl having a radial slot at the center, a driving member rotatable about an axis parallel to the axis of the ratchet wheel, and a crank pin carried by said driving member and projecting into the slot in thepawl, said slot being long enough to permit the crank pin to remain therein during the rotation of the driving member, and. the parts being so proportioned that the path of travel oithe center of the crank pin passes entirely around the pivotal axis of the pawl.

7. A member adapted to be drivenstep by step in either of two directions, a driving member adapted to be moved continuously in either of two directions, a ratchet wheel on the first of said members, a double-ended pawl cooperating with said ratchet wheel to cause one end of the pawl to drive the wheel in one direction and the other end of the pawl to drive the wheel in the opposite direction, a support for the pawl adapted to oscillate-through a small angle, andmeans driven by said driving member and engaged directly with the pawl to oscillate said support and cause one end of the pawl to act as the wheeldriving element as long as the driving member is moving in one direction and 'to cause the other end of the pawl to act as the wheel-driving element whenever the drivingmember is moving in the other direction. 1

8. In combination, a ratchet Wheel, an oscillatory pawl arm, a double-ended pawl pivoted on said arm in position to permit either end to be swung into operative relation to the teeth on the ratchet wheel, whereby the ratchet wheel may be turned step by step in either direction, a driving member adapted to be rotated in either direction about an axis parallel to the axis of the ratchet wheel; and means, including a pin carried by said driving memberat some distance from the axis of rotation of the latter, and guide elements on the 'pawl with which said pin slidably engages, to cause said pawl to be oscillated on said pawl arm to bring one end of the pawl or the other'into engagement with the ratchet wheel, depending 'upon the direction in which the driving member is turning, whereby the ratchet wheel will be driven step by step in one direction while the driving member is rotated continuously in one direction and the ratchet wheel will be driven step. byst'ep in the opposite direction when the direction of rotation of the driving member is reversed.

9. A ratchet wheel adapted to be turned step by step in either direction, a driving member adapted to be continuously rotated in either direction, a pawl arm adapted to oscillate through a small angle, a double-ended pawl on said arm in position to cooperate with the ratchet wheel to turn the latter in one direction'or the other depending upon which end of the pawl engages with the ratchet wheel, and a pin and slot connection between said pawl and the driving member including a slot in the pawl and a crank pin on the driving member.

10. A ratchet wheel adapted to be turned step by step in either direction, a driving member adapted to be continuously rotated ineither direction, a swinging pawl arm, a double-ended pawl on said arm adapted to cooperate with the ratchet wheel to turn the same in one direction or the other dependingvupon which end of the pawl engages with the ratchet wheel, and a driving connection between said pawl. andthe driving member including an elongated guide element located radially and at the center of the pawl, and a part mounted on the driving member at some distance from the axis of, rotation of the latter and slidably interlocked with the guide element on the pawl.

FRED C. AREY. 15 

